The disclosure relates to a semiconductor device fabrication technology, and more particularly, to a resistive memory device using resistance variations such as a non-volatile Resistive Random Access Memory (ReRAM), and a fabrication method thereof.
Recently, researchers have been studying next-generation memory devices that can substitute for Dynamic Random Access Memory (DRAM) and flash memory.
Among the next-generation memory devices is a resistive memory device which takes advantage of a property of a resistive layer that can switch between at least two different resistance states by a drastic change in resistance in response to a bias applied to the resistive layer.
A structure of such a resistive memory device and a switching mechanism thereof will be described briefly hereinafter.
A resistive memory device generally includes an upper electrode, a lower electrode, and a resistive layer disposed between the upper and lower electrodes. The resistive layer includes binary oxides or perovskite-based materials. When a predetermined level of bias is applied to the upper and lower electrodes, an oxygen vacancy filament may be generated in the resistive layer or a previously generated oxygen vacancy filament may disappear according to the applied bias. The oxygen vacancy filament functions as an electric current path. When an oxygen vacancy filament is generated, it signifies a set mode with low resistance. When an oxygen vacancy filament disappears, it signifies a reset mode with high resistance.
To reduce the reset current (Ireset) of such resistive memory device, Baek, I. G. et al. suggested forming a lower electrode in the form of a plug to reduce the contact area between the resistive layer and the lower electrode in an article entitled “Multi-layer Cross-point Binary Oxide Resistive Memory (OxRRAM) for Post-NAND Storage Application,” Electron Devices Meeting, IEDM Technical Digest, IEEE, 2005 which is incorporated by reference herein in its entirety.
However, since oxygen vacancy filaments are generated irregularly, the resistive memory device does not show a uniform characteristics distribution, such as a voltage/current distribution in the set/reset mode. This problem of non-uniform characteristics distribution becomes worse as resistive memory devices are miniaturized.